Proliferation and functional changes of pancreatic gastrin cells in neonatal rat

Although gastrin cells are not found in the adult pancreas, they are found transiently in the neonatal pancreas. It has been suggested that gastrin may play a role in pancreatic development. However, cell kinetics as well as the fate and the role of gastrin cells are not clear.

Proliferation and functional changes of pancreatic gastrin cells in neonatal Wister rats were studied by immunohistochemistry and [(3)H]thymidine autoradiography.

Numbers of pancreatic gastrin cells in neonatal rats showed a peak immediately after birth and then decreased rapidly. Gastrin cells were observed within approximately 2 weeks after birth in islets and within approximately 4 weeks after birth among exocrine cells. In contrast with the decrease of gastrin cell numbers, numbers of duodenal cholecystokinin cells increased remarkably after 7 days of age. Proliferative activity of acinar cells showed two peaks at age 2 days and 9 days. Despite a decrease in gastrin cell numbers, gastrin cells maintained a certain degree of proliferative activity. The "re-staining method" for gastrin and insulin revealed that immunoreactive cells for both gastrin and insulin were rarely found a few days after birth.

These results suggest that pancreatic gastrin cells do not die off or change to another type of endocrine cell and that some gastrin cells change to insulin cells.